SAN FRANCISCO, California — A man charged with the gruesome deaths of two jewelry store clerks and critically wounding the shop owner believed he had overpaid by about $300, prosecutors said in revealing a possible motive for a crime that has shocked the San Francisco Bay Area for its savagery.

Barry White Jr. (AP photo)

Barry White Jr. went to the Victoga jewelry store inside the San Francisco GiftCenter & JewelryMart on Friday to dispute a purchase he had made in May, Assistant District Attorney Scot Clark told reporters after White's first appearance in court Tuesday.

White complained that the jewelry "didn't have as many grams of the precious metal as it was supposed to" and believed he had overpaid, Clark said, declining to elaborate on the type of jewelry or metal it contained.

The 23-year-old from the eastern Bay Area city of Antioch is charged with two counts of murder and seven counts of attempted murder in the slaying of clerks Lina Lim, 51, of Daly City, and Khin Min, 35, of San Francisco, and the stabbing of the store's owner, Vic Hung, 50, who remains hospitalized in critical condition.

The attack was captured by store surveillance cameras, prosecutors say.

"The way that this individual went about killing these people was one of the most brutal, most calculating homicides I've viewed in my entire career," District Attorney George Gascon told reporters after the arraignment in San Francisco County Superior Court.

Court documents say White left the store to feed his parking meter and returned with a .38-caliber revolver and a folding knife, waiting until other customers left the store.

He then approached the jewelry counter and spoke to Hung and Lim. White reached into his pocket, pulled out the five-shot revolver and fired multiple times, striking both Hung and Lim but not killing them, prosecutors said.

As they fled to a back room, White approached Min, who was standing by the door. Min panicked and ran toward White instead of exiting, prosecutors said.

When his shots missed her, White pulled out a knife and "viciously cut her from ear to ear," Clark said.

Surveillance video shows White then going after Hung and Lim in the back room. Hung, who was fighting back, was slashed across his face and hands, while Lim was nearly decapitated.

Covered in blood, White then appears to reload his gun as several police officers arrive, responding to reports of shots fired. They approach him in front of the store not knowing if he was a victim or not, authorities said. White then opens fire on the officers as he runs toward a restaurant.

He surrendered after he ran out of ammunition, Clark said. Police later searched his vehicle and found a loaded AK-47 rifle and more ammunition, Assistant District Attorney Alex Bastian said.

White did not enter a plea Tuesday and was jailed without bail.

He's due back in court July 24, when a judge could decide whether to appoint White's private defense attorney, Steven Taxman, at the expense of San Francisco taxpayers, or appoint an attorney from the public defender's office.

Taxman, who has filed a motion asking to represent White despite his client's inability to afford him, said Wednesday that comments from the DA's office about White on Tuesday were out of line.

"Their comments have already deprived him of the ability to have a fair trial because he's already seen in the public eye as an evil monster," Taxman said.

Meanwhile, the public defender's office said Wednesday that it is against Taxman potentially defending White at taxpayers' expense.

"We oppose that because we feel the county should not pay for a private attorney when there's no conflict of interest in regards to us representing Mr. White," spokeswoman Tamara Aparton said.